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Community and Q&A

Yet another stucco question…

Monty Worthington | Posted in General Questions on

I have read as many articles on this site as I can on the best methods for stucco and have learned a lot – like staying away from OSB if possible under the stucco…

With that in mind I would like to ask a few questions and make sure I understand the best methods and options available.

Details are as follows: Exterior Plywood Sheeting installed over 2×6 wood frame – interior insulation TBD – Zone 3 Marine moderate – heating climate – no cooling, decent rain exposure and some wind driven rain.

Currently this is what is planned: Ext plywood sheathing (already installed) – 2 layers of building paper – 3 coat stucco with weep screed at bottom – at the top there are several parapet sections that the stucco will wrap over and meet with membrane roof from our flat roof sections (no metal cap on parapet)

So my questions are below…

Would taping the plywood seams before house wrap add any benefits?

There is no top vent in in this design – is that OK?

Would adding a drain layer like stucco wrap or home slicker help or work without the top venting?

Anything I am missing?

Thanks in advance!

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  1. GBA Editor
    Martin Holladay | | #1

    I believe that a drainage gap between the stucco and the sheathing is essential.
    More information here: To Install Stucco Right, Include an Air Gap.

  2. Monty Worthington | | #2

    Yes I have read that article a few times! - Anything on the rest of my questions.

    With regards to a drain layer my thinking is that it would be even more important in my case considering the lack of a vent cap at the top where the stucco meets the parapet...but I wanted to make sure I was correct. I had one contractor suggest 3 layers of building paper instead...

  3. Expert Member
    Armando Cobo | | #3

    Most every stucco manufacturer has their proprietary details that you must follow to have proper warranty. I suggest you find what brand you are using, go to their website and download their specs and installation instructions. All manufacturers do not have the same instructions.
    All that came out of the stucco lawsuits’ in the 90's.

  4. GBA Editor
    Martin Holladay | | #4

    Q. "Would taping the plywood seams before house wrap add any benefits?"

    A. If you choose a high-quality tape, then taping the plywood seams will lower your home's air leakage rate. That's good.

    Q. "There is no top vent in in this design - is that OK?"

    A. If you can vent your drainage gap at the bottom and top of your wall, the drying rate will be faster than in an unvented assembly.

    Q. "Would adding a drain layer like stucco wrap or home slicker help or work without the top venting?"

    A. Yes. The drainage layer is essential.

    Q.."Anything I am missing?"

    A. I'm not sure. Do you have an experienced stucco installer whom you trust? Are you willing to live with a siding that historically has a high failure rate? If the answers to these two questions is yes, you might be ready to proceed.

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